Android App Code:

note: I called the app Garage a Trois due to the openers three buttons, light, lock and door. /clever
My external opener is fingerprint authentication but most garages come standard with 4 digit PINs as a standard so we'll follow that "security" model.
There are five files in the project we'll go over.

login.xml - the xml file for Login.javacontrol.xml - the xml file for Control.javaLogin.java - the authentication activityControl.java - the command issuer.AndroidManifest.xml - tells the app what permissions to use and what orientation to allow